This invention relates in general to vehicle wheel end assemblies having aluminum steering knuckles and in particular to an anti-corrosion member adapted for use in such a vehicle wheel end assembly.
One example of a known vehicle wheel end assembly, indicated generally at 10, is illustrated in prior art FIG. 1. As shown therein, the prior art vehicle wheel end assembly 10 is associated with a front driven wheel (not shown) of a vehicle and includes a wheel hub 12, a bearing unit 14, a steering knuckle 16, and a brake rotor 18, and a dust shield 20.
The wheel hub 12 includes internal splines 12A for matingly receiving external splines of the axle spindle (not shown) for connecting the wheel hub 12 to the axle spindle for rotation therewith. The wheel hub 12 also includes a generally radially outwardly extending flange 12B, and a stepped bearing seat 12C. The wheel hub flange 12B includes a plurality of circumferentially spaced stud receiving holes 12D formed therein (only one of such stud receiving holes 12D is illustrated in prior art FIG. 1). The stud receiving holes 12D are adapted to receive studs 24 (only one of such studs 24 is illustrated in prior art FIG. 1), and nuts (not shown) for securing a rotatable brake component, such as for example the brake rotor 18 or a brake drum (not shown), and a vehicle wheel (not shown), to the wheel hub 12 for rotation therewith.
The bearing unit 14 is carried by the wheel hub 12 and includes a generally radially outwardly extending flange 14A. The bearing unit flange 14A includes a plurality of circumferentially spaced threaded mounting bolt receiving holes 14B formed therein (only one of such mounting bolt receiving holes 14B is illustrated in prior art FIG. 1). The mounting bolt receiving holes 14B are adapted to receive threaded ends of mounting bolts 22, which extend through corresponding openings 16A provided in the steering knuckle 16 and corresponding openings (not shown) provided in the dust shield 20, for securing the bearing unit flange 14A to the steering knuckle 16. Alternatively, the dust shield 20 can be attached by other suitable methods. Also, in some instances, the a dust shield 20 is not utilized.
When the bearing unit 14 is secured to the steering knuckle 16, a first outer surface 14C of the bearing unit 14 is disposed adjacent an outer surface 16C of the steering knuckle 16, and a second outer surface 14D of the bearing unit 14 is disposed adjacent an outer surface 20D of the dust shield 20. Alternatively, if a dust shield is not used, the outer surface 14D of the bearing unit is disposed adjacent an outer surface 16D of the steering knuckle 16.
Typically, the steering knuckle 16 is formed from cast iron and the bearing unit 14 is formed from steel. To reduce the weight of the assembly, it is known to form the steering knuckle 16 from aluminum. Unfortunately, when the steering knuckle 16 is formed from aluminum, galvanic corrosion can occur between the aluminum steering knuckle 16 and the steel bearing unit 14 at the respective adjacent surfaces 16C and 14C and 16D and 14D (if the dust shield 20 is not used); or if the dust shield 20 is used, galvanic corrosion can occur between the aluminum steering knuckle 16 and the bearing unit 14 and the dust shield 20 at the respective surfaces 16C and 14C and 14D and 20D. Such galvanic corrosion is undesirable because if the bearing 14 needs to be replaced, the galvanic corrosion can make it very difficult to remove the bearing unit 14 without causing damage to the steering knuckle 16.
To prevent the galvanic corrosion from occurring, it is known to coat the surfaces 14C and 14D of the bearing unit 14 (if the dust shield is not used); or if the dust shield is used, to coat the surface 14C of the bearing unit 14 and at least the surface 20D of the dust shield 20 with an anti-corrosive coating material, such as for example, paint, an E-coat, a powder paint or plating. However, the cost to coat the associated surfaces 14C and 14D of the bearing unit 14 with the above anti-corrosive coating is rather expensive since this is done after machining of these surfaces of the bearing unit 14. Thus, it would be desirable to provide an improved structure for a vehicle wheel end assembly which prevents galvanic corrosion between the aluminum steering knuckle and the steel bearing unit and yet is simple and inexpensive.
This invention relates to an anti-corrosion member adapted for use in a vehicle wheel end assembly vehicle wheel end assembly. The vehicle wheel end assembly includes a bearing unit formed from steel and including a pilot surface and a steering knuckle formed from aluminum and having a portion supported on the pilot surface of the bearing unit. The assembly further includes an anti-corrosion member disposed on the pilot surface of the bearing unit so as to be interposed between the bearing unit and the portion of the steering knuckle when assembled so as to prevent direct contact therebetween whereby galvanic corrosion between the steel bearing unit and the aluminum steering knuckle is prevented. The anti-corrosion member can be formed from plastic or formed from metal and coated with an anti-corrosive material.